Hello, I’m Emma, your kitchen companion and lifelong foodie. Growing up on an American farmhouse, I watched my grandmother harvest rhubarb straight from her garden each spring and transform it into bright, tangy desserts like this no-bake rhubarb dessert. Later, I fell in love with English teatime traditions—savoring crumbly bars over a steaming cuppa. This recipe for Oatmeal Rhubarb Bars brings those two worlds together: hearty, whole-grain oats meet the sweet-tart pop of summer rhubarb. It’s a celebration of nostalgia, simplicity, and the joy of sharing homemade treats.
These Oatmeal Rhubarb Bars are the very definition of rustic charm meeting bright, summery flavor. Imagine walking into a warm farmhouse kitchen at the height of rhubarb season: the air perfumed with the sweet-tart aroma of pink stalks simmering gently on the stove, mingling with the nutty scent of oats toasting in the oven. Each bite of these bars delivers a symphony of textures and tastes—the buttery, crumbly oat crust gives way to a jewel-toned ribbon of rhubarb filling, and finally, a crisp oat crumble topping that crackles delightfully under your fork, much like the buttery raspberry crumble cookies.
What I adore about these bars is how they celebrate rhubarb’s bright, tangy charm without drowning it in sugar or heavy creams. A buttery oat crust and a crunchy crumble top frame a jewel-toned ribbon of lemon-kissed rhubarb, creating the perfect sweet-tart balance. Simple to mix, easy to slice, and endlessly adaptable, they’re destined to be your new go-to summer treat.
Let me show you how to whip up these crowd-pleasing Oatmeal Rhubarb Bars—no fuss, all flavor!
Table of Contents
Why You’ll Love These Oatmeal Rhubarb Bars
- Bursting with Seasonal Flavor: Peak-season rhubarb offers a vibrant tang that cuts through the sweet oat layers for perfect balance—just like you’d find in our lemon cheesecake squares.
- Wholesome & Satisfying: Rolled oats add a nutty depth and chewy texture, making each bar as hearty as it is delicious.
- Effortless Entertaining: From picnic baskets to potluck tables, these bars travel well—no fragile frosting required.
- Make-Ahead Magic: Bake once, slice later; they keep beautifully in the fridge (and even freeze for a quick treat).
- Customizable Crunch: Fold in nuts, swirl in berries, or swap in gluten-free flour to suit your taste or dietary needs.
Ingredients for Oatmeal Rhubarb Bars
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Easy Oatmeal Rhubarb Bars: Rustic Summer Dessert
- Total Time: 1 hour
- Yield: 12 bars (3×4 grid) 1x
- Diet: Vegetarian
Description
A buttery oat crust and crisp oat crumble sandwich a tart-sweet, lemon-kissed rhubarb filling—perfect for summer gatherings, afternoon tea, or make-ahead snacks.
Ingredients
2 cups rolled oats
1 cup all-purpose flour
1 cup brown sugar
1 cup chopped rhubarb
1/2 cup unsalted butter
1/2 teaspoon baking powder
1/2 teaspoon cinnamon
1/4 teaspoon salt
1/2 cup water
Instructions
Preheat & Prep
Preheat oven to 180 °C (350 °F). Line a 9×13 inch pan with parchment, leaving a 1″ overhang for easy removal.Make Crust
In a bowl, whisk oats, flour, sugar, salt, and cinnamon. Add butter; cut in with a pastry cutter until coarse crumbs form.
• Reserve 1¼ cups for the topping.
• Press the remaining mixture firmly into the pan. Chill 10 minutes.Assemble Filling
Toss rhubarb with sugar, cornstarch, vanilla, and lemon zest. Spread evenly over chilled crust.Add Topping
Sprinkle reserved oat mixture over the rhubarb layer.Bake & Cool
Bake 35–40 minutes until topping is golden and filling bubbles. Cool completely on a wire rack (about 1 hour) before slicing into 12 bars.
Notes
Bolder Rhubarb Flavor: Use 3–4 cups rhubarb; reduce water to ¼ cup (or omit) to avoid sogginess.
Nutty Upgrade: Fold ½ cup chopped walnuts or pecans into the topping.
Citrus Twist: Swap lemon zest for orange or lime.
Make-Ahead: Assemble, cover, and refrigerate unbaked up to 24 hours; bake straight from the fridge, adding 2–3 minutes.
Storage: Airtight container at room temperature up to 2 days or refrigerated up to 5 days. Freeze layered between parchment up to 1 month.
- Prep Time: 20 minutes
- Cook Time: 35–40 minutes
- Category: Dessert / Snack
- Method: Baking
- Cuisine: American farmhouse
Nutrition
- Serving Size: 1 bar
- Calories: 230 kcal
- Sugar: 12 g
- Sodium: 120 mg
- Fat: 9 g
- Saturated Fat: 5 g
- Unsaturated Fat: 3 g
- Trans Fat: 0 g
- Carbohydrates: 32 g
- Fiber: 3 g
- Protein: 3 g
- Cholesterol: 30 mg
Keywords: Oatmeal Rhubarb Bars, Rustic Dessert, Summer Baking
Step-by-Step Instructions for Oatmeal Rhubarb Bars
- Preheat & Prep Pan
Preheat your oven to 175 °C (350 °F). Grease a 9×13 inch baking pan or line it with parchment paper. - Mix Dry Ingredients
In a large bowl, stir together the rolled oats, flour, brown sugar, baking powder, cinnamon, and salt until evenly combined. - Incorporate Butter
Pour the melted butter into the dry ingredients and mix until you have a crumbly dough. - Form the Base
Reserve about two-thirds of the oat mixture. Firmly press that reserved portion into the bottom of your prepared pan to form an even crust. - Add the Rhubarb
If your rhubarb is especially dry, toss it with the water so it stays juicy in the bake. Spread the chopped rhubarb evenly over the oat base. - Top & Bake
Sprinkle the remaining oat mixture over the rhubarb layer. Bake for 30–35 minutes, or until the top turns golden brown and the rhubarb filling is bubbling at the edges. - Cool & Slice
Remove from the oven and let cool completely in the pan. Once cooled, slice into 12 bars and enjoy!
Tips for Perfect Oatmeal Rhubarb Bars

- Bolder Rhubarb Flavor: Use 3–4 cups chopped rhubarb and reduce the water to ¼ cup (or skip it entirely). This keeps your bars from getting soggy while giving you that extra bright tang.
- Chill the Crust: After pressing the base into the pan, chill it for 10–15 minutes before adding the filling. A firm crust helps the bars hold together when you slice them.
- Even Rhubarb Pieces: Try to cut your rhubarb into uniform ½″ pieces so they cook evenly and you don’t end up with under- or over-done bites.
- Add a Nutty Crunch: Stir in ½ cup chopped pecans, walnuts, or sliced almonds into the topping mix for extra texture and flavor.
- Citrus Twist: Swap the lemon zest for orange or lime zest to subtly change the flavor profile. A little zest goes a long way!
- Sweetener Swap: Replace brown sugar with coconut sugar or maple syrup for a deeper, caramel-like sweetness. If using maple syrup, reduce any added water by a tablespoon.
Enjoy experimenting and making these bars your own—every tweak adds a new twist of deliciousness!
Frequently Asked Questions About Oatmeal Rhubarb Bar
1. Can I use frozen rhubarb?
Yes—thaw and drain excess liquid first, then toss with sugar and cornstarch as directed. You may need an extra minute or two of bake time to evaporate moisture.
2. How do I make these bars gluten-free?
Substitute a 1:1 gluten-free all-purpose flour blend in both the crust and topping. Ensure your oats are certified gluten-free if sensitivity is a concern.
3. What’s the best way to store leftovers?
Keep cooled bars in an airtight container in the refrigerator for up to 3 days. For longer storage, layer with parchment and freeze for up to 1 month; thaw overnight in the fridge.
4. Can I mix other fruits with rhubarb?
Absolutely! Strawberries, raspberries, or cherries pair beautifully. Use equal portions fruit-to-rhubarb and adjust sugar by an extra tablespoon if your berries are particularly tart.
5. How do I reheat a single bar?
Pop it in a 160 °C (325 °F) oven for about 5 minutes, or microwave for 10–15 seconds for a warm, freshly baked feel.
Conclusion
These Oatmeal Rhubarb Bars are more than just dessert—they’re a slice of summer memories and heartfelt baking traditions. Whether you’re serving them at your next gathering or enjoying a quiet afternoon with tea, they’re guaranteed to brighten any table. I hope you fall in love with their rustic charm and delightful tang, just as I have. Happy baking, and please share your favorite twists in the comments below!